Currently, refrigerated fish sperm is stored for short periods, i.e., hours to a few weeks, in a variety of containers. Some of these containers include 50-ml conical centrifuge tubes, freezer storage bags, and miscellaneous plastic storage containers. Once the sperm is placed into these containers, the container with sperm is stored in a refrigerator at 2-4° C. When the sperm is collected in the field on a stream or lake bank, the sperm is stored in a cooler containing wet ice to maintain the temperature close to about 2-4° C. Unless the container is handled after the sperm is introduced, there is no motion imparted to the sperm and no mixing between the sperm and any oxygen or atmospheric air layer above the sperm. This is contrary to how sperm or other biological products would be maintained in nature. In nature the male fish would be in almost constant motion, which would allow for continuous oxygen replenishment from the animal's circulatory system to the testes where the sperm are contained.
The literature concerning fish sperm maintenance, as well as experience, document that repeated or continuous mixing of the sperm in an oxygenated atmosphere improves sperm viability during refrigerated storage. This need is greatest in the field, where collection of fish sperm is often undertaken. However, in the laboratory or commercial storage for aquaculture, the sperm should ideally be aerated or oxygenated during this cold storage period.
Presently, the only known method of oxygenating and mixing the sperm is by manually inverting the sperm containers every twelve hours. This does not provide the continuous mixing and oxygenation of sperm that occurs in vivo.
There are no known devices within the scientific, conservation, or aquaculture community for continuously oxygenating or aerating sperm or other biological materials which require continuous aeration or oxygenation during storage. The only other known devices which are similar, but which are unsuitable for field use, is found in human blood collection and storage.
Among the devices that can be used in blood collection or storage are those described in U.S. Pat. No. 2,840,915 to Drummond et al.; U.S. Pat. No. 4,027,735 to Floyd; U.S. Pat. No. 5,282,982 to Wells; U.S. Pat. No. 3,480,015 to Gonzalez; and U.S. Pat. No. 4,923,449 to Toya et al.